Manufacture of hydrocarbons



'ug. 13, 1935. G EGLOFF v 2,010,949

MANUFAGTURE or` HYDRocARBoNs Filed March 24, 1935 Coole?q fece VerPatented Aug. 13, 1935 PATENT lOFFICE MANUFACTURE OF HYDROCARBONS GustavEgloff, Chicago, Ill., assigner to Universal Oil Products Company,Chicago, Ill., a corporation of Delaware Application March 24, 1933,Serial No. 662,472

2 Claims.

This invention relates more particularly to the manufacture, bysynthetic reactions, of hydrocarbons utilizable as constituents of motorfuel.

In a more specific sense the invention has reference to a process whichmay be employed to supplement the cracking process and increase theyield of high antiknock material obtainable. The particular steps bywhich this object is accomplished and the novel and useful effectsproduced will be shown in the following specification.

Gasoline boiling range hydrocarbons produced by decomposition reactionsaccompanying the pyrolysis of relatively heavy fractions of petroleumcontain relatively higher percentages of unsaturated hydrocarbons ofboth an open chain and a closed chain character than similar boilingrange straight run gasolines due to the dehydrogenating character of thedecomposition reactions involved in cracking. The olefins and cycliccompounds thus produced are characterized by a greatly reduced tendencyto detonate when used as fuel in internalcombustion engines so thatcracked motor fuels are uniformly superior to straight run for presentday automobile engines which for the most part employ high compressionratios.

When attempts are made to increase the antiknock value of crackedgasolines beyond a certain point, losses in gas and coke reach seriousproportions and a balance must be struck between yield and quality ofproduct. The present process may be employed to produce greatlyincreased yields of high antiknock gasoline hydrocarbons while utilizingthe olenic constituents of the xed gases, which for the most part areused only as fuel in present commercial practice.

In one specic embodiment the invention comprises treatment of aromaticor similarly reactive hydrocarbons with olens in the presence ofsulphuric acid to produce alkylated derivatives, separating saidderivatives from sludge reaction products and fixed gases, fractionatingsaid derivatives to produce a high antiknock overhead gasoline which iscooled, condensed and collected and a reflux comprising hydrocarbonsboiling higher than gasoline, and recycling said reflux to furthercontact with aromatics and sulphuric acid to produce further yields ofgasoline boiling range fractions.

The reactions between olens and aromatic hydrocarbons in the presence ofsulphuric acid catalyst which lead to the production of alkylatedderivatives of aromatics are quite general and are typified by thefollowing equation showing the condensation of propylene and benzol toform iso-propyl benzol:`

CxBq -I- CIHI 1:2 CIHLCIH;

Propylene A Benzol Iso-propyl benzol The mechanism of this and similarreactions involving other aromatics and other olens is apparentlyexplained by assuming rst the formation of alkyl sulfates and aromaticsulphonic acids and second the interaction of these primary acidderivatives to form the alkyl ring compound while the acid isregenerated. Some side reactions occur, of course, resulting on the onehand in loss of sulphuric acid due to oxidation reactions and theformation of undecomposable sulfo derivatives but in general thereactions may be forced from left to right as shown in the equation bysuitable choice of conditions, particularly in respect to limiting thestrength of the acid employed and the maintenance of a temperature notfar removed from ordinary atmospheric.

In all such alkylating reactions there is an attendant formation of morehighly alkylated derivatives than the one shown on the right `hand sideof the equation, that is, di, tri, tetra and possibly even more highlyalkylated derivatives. Many of the more highly alkylated aromatics haveboiling points too high to permit their use. .m as components of motorfuel and it is the purpose of the present invention to Work over-thesehigher boiling fractions which are incidentally produced and effectivelyreform them into hydrocarbons of desired boiling range, therebyincreasing the yield of gasoline. Even when the amount of hydrocarbonsboiling above the end point desired in gasoline is not excessive theremay be too great a production of compounds boiling within the upperrange of gasoline since many of the compounds formed in the reactionsbetween propylene, butylenes and amylenes boil within the range ofapproximately 200 to 240 C. Thus not only may the compounds boilingabove the gasoline end point be de-alkylated but also those boilingwithin the upper boiling range which are produced in too great quantityfor a balanced gasoline.

To indicate in a general way the sequence of operations involved in thepresent invention the attached diagrammatic drawing has been preparedwhich shows by the use of conventional iigures in side elevation anarrangement of elements in which the process may be conducted althoughthe invention does not limit it to the particular details of the presentdrawing since other modiiications of plant equipment may be employed.

Referring to the drawing, line I is an inlet gas line through which gasmixtures containing olens may be admitted through valve 2, it beingassumed that the gases are under sufncient pressure to take care of thepressure needs of the treatment both in respect to static conditions andnecessary ow differentials. Thus olenic gas mixtures resulting from thecracking of petroleum or other hydrocarbon oils either for gasoline orgas production may be admitted, the olenic content of such gases varyingwith the charging stock used and the conditions of cracking. Sulphuricacid is most effective in causing the union of oleflns higher thanethylene with aromatics and the most effective mixtures therefore arethose containing high percentages of propylene, the butylenes and theamylenes which may run from 30 to 40% of many gas mixtures encounteredas by-products in oil cracking operations.

Benzol or other aromatic homologs or mixtures thereof may be introducedto the system through line 3 containing control valve 4 and be deliveredby pump 5 through a line 6 containing control valve 1 to mix with thegases in line I.

The necessary amount of sulphuric acid may be introduced through line 8containing control valve 9 and be delivered by pump I0 through a line IIcontaining a control valve I2. 'Ihe acid may be added also by utilizingthecustomary blow case although this is not shown in the presentdrawing. Olefinic gases, aromatic hydrocarbons (both fresh compoundsfrom outside the process and recycled overalkylated materials from line58) and sulphuric acid are thus brought together in line I and may bepassed through perforated plates or other obstructions or mixing devicesto insure thorough contact, the mixture passing through a cooling coilI3 for maintaining some optimum low temperature which will depend uponthe character of the hydrocarbons undergoing re` action and the productsdesired. In general since the object of the invention is to handle thealkylation reactions so that improved yields of compounds suitable foruse in gasoline are produced, the temperature is maintained at somefairly low point and may be carried as low as 30 to 40 F. if desired.

The proportions of olefin-containing gas, sulphuric acid, fresharomatics and recycled highlyalkylated aromatics are preferably adjustedto produce the optimum possible yield of gasoline boiling rangefractions. Owing to the number of factors involved and the highlycomplex nature of the reactions, particularly when mixtures of botholens and aromatics are used, it is not always possible' to calculatethe best conditions of operation but theseA may be adjusted for anygiven set-up after a few experimental trials.

` The reaction products consisting of sludge acid, alkylatedhydrocarbons, unchanged aromatics and residual gases then pass through aline I4containing control valvey I5 and enter a separator I6. In thisseparator layer I1 has been `marked olf to indicate a layer of settledsludge oleflnic content indicates. or used as fuel if the olens havebeen economically removed.

Since a certain amount of alkyl sulfates may be dissolved in the liquidhydrocarbon reaction products it is usually advantageous to destroythese by reaction with caustic soda both because they add sulphur to theproducts and because they have a tendency to decompose in the subsequentfractionating step and cause difficulties due to foaming. Thus causticsoda solution may be picked up by pump 3IJ through line 28 containingcontrol valve 29 from a source of supply not shown and pumped throughline 3| containing control valve 32 into line 25 containing thehydrocarbon effluent from the separator, the mixture of neutralized oiland sludge caustic then passing through valve 26 to separator 21. Thisseparator may be provided with a gas release line 33 containing controlvalve 34 for releasing any gas which may be carried over, this gas beinggenerally similar to those released through line 2I and disposed of in asimilar manner. Line 35' containing control valve 36 indicates a drawline for the removal of the spent neutralizing caustic.

The alkylated hydrocarbons are then preferably subjected tofractionation and the heavier portions thereof partially de-alkylated inthe second stage of the process. To this end line 35 containing controlvalve 36 leads to a pump 31 which discharges through line 38 containingcontrol Valve 39 into and through a tubular heating element 40 disposedto receive heat from furnace 4I. During passage through the heatingelement the mixture is heated sufficiently to enable the substantiallycomplete separation and removal of gasoline fractions, the heated andpartly vaporized hydrocarbons then passing through line 42 containingcontrol valve 43 into a fractionator 44, of suitable design and capacityfor eiectively removing the gasoline as an overhead product.

The gasoline vapors evolved at this po-int as a nal product of theprocess are subjected to the ordinary processes of condensation andcollection, passing through line 45 containing control valve 46,condenser 41, through run-down line 48 containing control valve 49 andentering receiver 50 which has a gas release line 5I containing controlvalve 52 and a liquid draw line 53 containing control valve 54 for theremoval of the product to storage.

The hydrocarbon refluxes from fractionator 44 which comprisehydrocarbons heavier than gasoline are then preferably returned to theoriginal treating zone for de-alkylation. As previously mentioned, abalance is struck in this zone in respect to fresh or unalkylatedaromatic and the amount of acid and gas used so that the best yield ofgasoline is obtained at this point. I have found that these reactionsinvolving the shift of alkyl groups from the more highly alkylated tothe less highly alkylated hydrocarbons occurs readily so that theprocess is in every sense operatable and efficient.

Thus the high boiling over-alkylated compounds are discharged from thefractionator through a line 55 containing control valve 56 to arecycling pump 51 which returns the refluxes back to the originaltreating zone through line 58 containing control valve 59.

The reactions occurring when "over-alkylated" hydrocarbons are returnedto contact with fresh aromatics and sulphuric acid may be typified bythev equation given below. However, the reaction shown is of arelatively simple character in comparison to the sum total of thosewhich may occur when reaction is brought about between freshhydrocarbons and alkylated products of a highly mixed character such asmay have been produced when alkylating aromatics with mixed olefins inthe rst stage.

HzSO

CsH4(CaH1): CaHe 1:2

Di-isopropyl benzol Benzoi Mono-isopropyl benzol Cracking yields Percentby Product Yield weight of charge Gas, 1.20 sp. gr 700 cu. itA /bbLoioil 20 Gasoline, 56 A. P. I. 65% by volume 56 gravity. Intermediaterecycle stock, 5% by volume 5 28 A. P. I. gravity. Coke 60lbs./bbl. ofoil 19 The gas produced may contain approximately 20 to 25% of olefinssuch as propylene and the butylenes with the percentage of propylenepredominating.

The total fixed gases thus produced may be passed together withapproximately 6 gals. of commercial benzol per bbl. of stock cracked andabout 8% by weight of 66 B. sulphuric acid (based on the benzol) throughmixing and cooling devices generally similar to those described inconnection with the drawing. By continuously returning theover-alkylated products from the fractionator to the primary treatingstage according to the invention, the overall yield of syntheticproducts per barrel of oil originally cracked may be approximately 7gallons, this product having an antiknock value twice that of theoriginal benzol which was added to combine with the olefins. By blendingthis synthetic liquid with the cracked gasoline as produced the volumeyield of gasoline is therefore raised from to 81%, the antiknock valuebeing at the same time raised from 64 to 81.

On a basis of the foregoing figures there is no question of the value ofthe process when operated in conjunction with cracking since both theyield and quality of the gasoline is increased and a large percentage ofthe gaseous products are conserved. However, the specific numerical datagiven are not to limit the scope of the invention thereto nor is thedescription of operations given in connection with the drawing toexercise a limiting action since many other types of plants may beutilized to eiect similar economies.

I claim as my invention:

1. In a process for the treatment of aromatic hydrocarbons of thebenzene series with normally gaseous olefinic hydrocarbons in a reactionzone in the presence of a contact agent comprising sulphuric acid toproduce alkylated derivatives suitable for motor fuel, the improvementwhich comprises distilling said derivatives to produce a product withinthe boiling range of motor fuel possessing high anti-knock propertiesand a reflux condensate higher in boiling range than motor fuel,cooling, condensing and collecting the overhead product of distillation,and returning the reflux condensate to the reaction zone.

2. In the alkylation of aromatic hydrocarbons of the benzene series byreaction thereof in a reaction zone with normally gaseous oleiinhydrocarbons and wherein there is formed a mixture of alkylatedderivatives boiling within and above the gasoline range, the improvementwhich comprises separating said mixture into a fraction boiling withinthe gasoline range and a heavier fraction, returning said heavierfraction to the reaction zone and dealkylating the same thereinconjointly with the alkylation of the aromatic hydrocarbon.

GUSTAV EGLOFF.

